2010-04-29

Spirit Sol 470

We're in that weird phase where we're planning in the blind. The sequences we wrote yestersol haven't even been uplinked to the rover yet, much less executed, so clearly we haven't gotten the downlink yet. And today's are going to look similar to yesterday's, so we could blow two whole days if we did something wrong yesterday. So I ask Chris -- RP-2 today -- to look them over. In theory, if he finds a problem, we could fix it and uplink the result instead of what we planned yesterday. Not that our mission manager would let us get away with that. But Chris doesn't find anything anyway, so it's moot. At least I'll be able to sleep a little better.

In theory.

Yesterday we did a 4x4 subset of the total 4x6 mosaic. Today we pick up where we left off, doing the remaining 2x6 subset of the mosaic. Then we brush off a spot with the RAT and place the APXS there. Overall, not such a bad day -- yesterday was harder.

The hard part is to fit in the MI sky flats. This is where we take microscopic images of the sky. Yes, you read that right. It's a calibration thing. The problem is that there are restrictions on how we take the sky flats, and it's awkward to satisfy them all at once. First, the MI must be aimed at least 90 degrees away from the sun. Second, the sky-flat images must be taken late in the day, after about 14:00. Third, the MI needs an unobstructed view of the sky, so no part of the rover body or the terrain can be in the way. Fourth, it must be aimed about 40 degrees above the horizon.

The first and second constraints combine to force the MI to aim to the rover's right. So now the problem is to find a solution where the MI is aimed to the right, 40 degrees above the horizon, without any terrain or rover body in view. There doesn't seem to be any way to do this. In one wrist configuration, the rover deck blocks our view when the MI is close to the WEB and the IDD self-collides when the MI is pushed farther from the WEB. In the other wrist configuration, we can choose between having the rover deck in the way or running into a hardstop -- with the arm otherwise in the needed pose, the 40-degree elevation is in a "blind spot" where the turret can't aim the MI.

This means we can't do the sky flats, which makes me feel very bad. The MI PUL, Ken, is such a nice guy, and it's been literally 400 sols since he's had this calibration done. Then at last they make room for it in the plan, and I can't find a solution for him. It's not my fault that the solution's not there to be found, but I still feel bad about it.

But otherwise, the sol goes well. We're practically drunk on power -- 937 Watt-hours thisol, more than we had when we landed. Thanks, dust devils! And the sequencing proceeds without any major hiccups.

At the end of the day, Steve fills us in on the science team's current thinking about where we want to go from here. First, images taken from the other side -- that is, the current side -- of Larry's Lookout (a landmark partway up Husband Hill, which we passed on the way up) have apparently made the scientists even more interested in it, so we're going to head back downhill to it. Downhill is the wrong direction, I want to say (damn, I want to see the view from that summit!) -- but I'm just the chauffeur, so I wisely keep my mouth shut. The right direction is wherever the science is, and if that's downhill from here, then so be it.

On the way back down to Larry's Lookout, we'll check out another rock near this one, then this area called Jib Sheet. We probably won't get quite close enough to Larry's Lookout to touch it, since there's a steep pile of soft sand in the way, but we'll take highly detailed pictures from as close as we can. (Like Burns's Cliff, Steve points out.) Then we turn back around and start slogging up the hill again.

"Sorry about that," Steve says. "This is the best exposed geology we'll see this side of Husband Hill, so we gotta do it."

That's okay, it really is. The big disappointment from today comes from an unexpected direction, when Chris finds a way we could have done the MI sky flats after all. It's a configuration I thought I'd tried, but obviously not. So now I feel twice as bad about not finding a way to do it, because there was a way to be found. I just didn't find it.

(And writing this, it occurs to me there was always a way anyhow. The IDD's elbow joint is fully double-jointed; we could simply have swung the turret up so that it was above the elbow rather than below it. Then aiming the MI for the sky flats would have been trivial -- the rover deck is never in the way in that pose. Oh, I am dumb sometimes, I truly am.)

I swallow my pride and send Ken and Steve email about this. We couldn't do the sky flats today, but we'll still be here over the weekend. Maybe we'll squeeze it in tomorrow.